Chmod Calculator
Free online chmod calculator to visualize and calculate Linux file permissions with checkboxes. Instantly convert between numeric (755, 644) and symbolic notation (rwxr-xr-x). Supports special permissions like setuid, setgid, sticky bit.
What is chmod?
chmod (change mode) is a Linux/Unix command that changes the access permissions of files and directories. It determines who can read, write, or execute a file.
What does chmod 755 mean?
chmod 755 means the owner has read, write, and execute permissions (7=rwx), while group and others have read and execute permissions (5=r-x). Commonly used for executable scripts and directories.
How to manually calculate chmod values?
Each permission has a numeric value: read=4, write=2, execute=1. Add these values for each category (owner, group, others). For example, owner with rwx = 4+2+1 = 7.
What do rwx permissions mean?
rwx stands for read (r), write (w), and execute (x). Read allows viewing file content, write allows modifying it, and execute allows running it as a program or script.
What are special permissions like setuid, setgid, and sticky bit?
setuid (4000) makes a file run with the owner's privileges, setgid (2000) makes it run with the group's privileges, and sticky bit (1000) restricts deletion of files in a directory to the owner only.
What permissions should web server files have?
Web files typically use 644 (rw-r--r--) for HTML/CSS/JS files and 755 (rwxr-xr-x) for directories and CGI scripts. Never use 777 as it allows anyone to modify files.
How to use symbolic notation with chmod?
Symbolic notation uses letters like u (user), g (group), o (others), a (all) and operators + (add), - (remove), = (set). For example, chmod u+x file adds execute permission for the owner.
Is this tool private?
Yes, this chmod calculator runs 100% in your browser. No data is sent to any server, ensuring complete privacy and security.